Electronic Fuel Injection

Electronic Fuel Injection (EFI) system is an electronically controlled system operated by incoming airflow. The EFI system also contains a feedback system, which measures oxygen content of exhaust gases and maintains air/fuel ratio near 14.7:1. The EFI system has 3 sub-systems: air intake system, fuel system and computerized engine control (ECA/ECU).

Each cylinder has a solenoid-operated injector, which sprays fuel toward back of each intake valve. Injector bodies consist of solenoid-actuated pintle and needle valve assembly. Injector flow orifice is fixed, and fuel pressure at injector tip is constant. Atomizing spray is obtained by shape of pintle.

ECA/ECU controls fuel injectors and meters pulse width or number of time each injector is energized. Each injector receives battery voltage through ignition switch circuit. ECA/ECU completes ground circuit to energize injector. ECA/ECU receives inputs from engine sensors to compute fuel flow necessary to maintain proper air/fuel mixture throughout entire engine operational range.